1. Field of the Invention
The present invention generally relates to pallets and, more particularly, to spill pallets which support liquid containing drums and are capable of retaining spilled or leaked liquid from such drums.
2. Description of the Related Art
Spill pallets have developed in accordance with guidelines of the United States Environmental Protection Agency (EPA), and are designed to support one or more drums and to provide a reservoir to contain liquid should it escape or leak from the drums. The EPA requires liquids having more than 500 parts per million of poly-chlorinated biphenyls (PCBs) to be stored in DOT-17E drums, or equivalent sealed containers, and that those drums be stored in a diked area with an impervious and drainless floor. The diked area is provided by the spill pallet and must have a liquid-receiving volume equal to at least twice the volume of the largest container stored on the pallet.
U.S. Pat. No. 4,361,232, which issued to Olmsted on Nov. 30, 1982, is illustrative of a basic type of spill pallet developed in accordance with EPA requirements. In the Olmsted patent, an open-topped box comprising a solid bottom wall and a series of upstanding side walls serves as the spill pallet. The drums are carried or placed on the bottom wall of the spill pallet, and the pallet provides an available volume which is twice that of the largest container placed therein. The side walls are laterally unsupported, but do not tend to deform because they are not load bearing.
Spill pallets of the type disclosed in the Olmsted patent contain spills but, due to the fact that the side walls extend above the drum-supporting bottom, placement of drums within the pallet is difficult. Also, since the drums rest within the area intended for liquid containment or retention, the drums will be partially immersed in liquid should a leak or spill occur, making spill detection and clean-up more labor intensive and time consuming.
In response to the shortcomings of the basic spill pallet embodied by the Olmsted patent, a next generation of prior art spill pallet was developed by the assignee of the present invention. This prior art spill pallet, which is illustrated in FIGS. 1 and 2, supports the bottom of the drums vertically above the spill retention or containment area.
The prior art spill pallet 10 is shown to include a bottom wall 12 and a series of side walls 14. The sidewalls 14 cooperate to provide a rectangular peripheral ledge or rim 16. The bottom wall 12 has projecting upwardly therefrom an inner support 18 which is generally cross-shaped, as illustrated. The cross-shaped support 18 provides an upstanding ridge 20 and divides or separates the pallet into a series of four bowl-shaped recesses 22. The terminal ends 24 of the cross-shaped support 18 are spaced from the side walls 14 of the pallet 10. Fluid communication channels 26 are defined by the terminal ends 24 and the side walls 14 and provide a fluid communication path between adjacent bowl-shaped recesses 22.
A pair of drum-supporting grates (not shown) rest upon the upper surface of the cross-shaped support 18 and the rim 16. The grates are separated or spaced-apart by the ridge 20. Since the terminal ends 24 of the cross-shaped support 18 are spaced from the side walls 14, they provide no lateral support for the side walls 14 and the side walls tend to bulge or otherwise deform when loaded.
The spill pallet shown in FIGS. 1 and 2 addresses the disadvantages associated with the basic spill pallet illustrated in the Olmsted patent. However, the side walls 14 of the illustrated spill pallet, like its predecessors, are unsupported laterally. While this is not a disadvantage in the Olmsted spill pallet, since the side walls 14 of the illustrated prior art spill pallet are load bearing they have a tendency to deform. This potential instability may limit the load-bearing capability and useful life of the spill pallet illustrated in FIGS. 1 and 2. Therefore, there exists a need in the art for a spill pallet which spaces the drum-supporting surface upwardly from the spill containment and retention area while having a laterally supported, stable, load-bearing side wall structure.